The invention relates to a combination of:

- an electromagnetic switch, such as a vacuum interrupter, comprising:

+ at least an electromagnetic opening coil for moving the switch to an open state;

+ a first power supply, preferably a capacitor, for driving the opening coil; and

+ a control switch for controlling the power of the first power supply to the electromagnetic opening coil;

- a controller having an open command input for receiving an opening command, an open output for controlling the control switch of the electromagnetic switch and a power supply input;

- an external power supply connected at least to the first power supply of the electromagnetic switch and to the power supply input of the controller.

Such a combination is for example known from EP 1986302. Switchgear such as a vacuum interrupter is typically used for medium and high voltage applications, to switch a power supply to a bad, like for example an electric pump. With such switchgear, the circuit responsible for opening the vacuum interrupter is a very safety critical part of the controller. This opening circuit opens the vacuum interrupter contacts after receiving any external opening command from a user or from a protection relay to break the electric circuit between the supply and load during any normal or abnormal condition.

The controller of the switchgear is powered by an external power supply. If external power supply fails, then the switchgear controller will be switched-off and will not able to perform any vacuum interrupter opening or cbsing operation after receiving any command.

However during this period of external power failure it is required to keep the vacuum interrupter opening circuit alive for at least a few hours for opening the contacts if an opening command is received.

Typically the opening circuit of the controller is at least powered from the energy stored in vacuum interrupter opening capacitor or from a separate backup power supply such as described by EP 1986302. The size of the opening capacitor has to be bigger as to store the sufficient energy for powering the opening circuit for few hours and also to provide sufficient energy to activate the electromagnetic opening coiL Or a separate power backup needs to be provided.

Generally in software implemented switchgear controllers, the software keeps the controller into sleep mode during external power failure for less power consumption, such as for example described in US 2013015712. But other parts of the combination, like a DC to DC converter, which provides the power supply to the microcontroller and opening circuit in the controller need to be active and will continue to consume power.

For all the known prior art solutions, the period in which the opening circuit can function during a power failure is limited, because still some parts of the controller will consume power.

It is an object of the invention to reduce or even remove the above mentioned disadvantages.

This object is achieved with a combination according to the invention, which combination is characterized by an opening control switch having an input terminal and an output terminal, wherein the input terminal is connected to the first power supply of the electromagnetic switch and wherein the output terminal is connected to the open command input and to the power supply input of the controller.

When a power failure of the external power supply occurs, the controller will be fully switched-off. This ensures that no power is drained. If the electromagnetic switch needs to be switched to the open position, the opening control switch will be cbsed, for example manually. This will cause power of the first power supply of the electromagnetic switch to be supplied to the controller, such that the controller can start up. Furthermore, the power of the first power supply is supplied to the open command input of the controller to supply the command for opening the electromagnetic switch. So, as soon as the controller has been started up, it will detect the command on the open command input and start the sequence for opening the electromagnetic switch. Thus, with the invention only power is drained from the first power supply for the controller during power failure of the external power supply once the electromagnetic switch needs to be opened. As a result, the power failure can be virtually indefinite and with the invention, it will still be able to switch the electromagnetic switch to the open position.

The only limitation will be any internal power leakage of the first power supply.

In an embodiment of the combination according to the invention a first voltage converter is arranged between the external power supply and the power supply input of the controller and wherein a second voltage converter is arranged between the output terminal and the power supply input of the controller.

The first and second voltage converters are used to bring the voltage of the external power supply or the first power supply to a level at which the power can be supplied to the controller and electronics circuits.

As such voltage converters consume some power during converting, the second voltage converter is arranged to the output terminal of the opening control switch, such that the converter is only supplied with power when the opening control switch is closed.

In a preferred embodiment of the combination according to the invention the electromagnetic switch further comprises an electromagnetic cbsing coil for moving the switch to a closed state and a second power supply, preferably a capacitor, for driving the cbsing coil, which second power supply is connected to the external power supply; wherein the second power supply is connected to the first power supply via a diode with the forward direction of the diode towards the first power supply.

For example with vacuum interrupters, there are both an electromagnetic cbsing coil and an electromagnetic opening coiL Both coils have corresponding power supplies, typically capacitors.

Once a power failure of the external power supply is present, the electromagnetic switch only needs to be opened. Cbsing, after opening, is no bnger required in such a power failure condition. So the power of the second power supply can be used also for the opening circuit. So, by connecting the second power supply via a diode to the first power supply the second power supply can be used to charge the first power supply if the power sbwly drains from the first power supply due to internal leakage. This will extend the period in which the electromagnetic switch can still be controlled to an open position during a prolonged power failure.

Preferably the combination further comprises a charger unit arranged between the external power supply and the first power supply and / or second power supply of the electromagnetic switch. The charger unit is used for ensuring that the first and second power supply are full charged when the external power supply is functional, such that upon a power failure, the first and second power supply can optimally be used for controlling the electromagnetic switch to an open position at a desired moment during the power failure.

Furthermore it is preferred that the opening control switch is both manually and electromagnetic operable. This albws for a user to manually switch the electromagnetic switch to an open position or to have an external control system cbse the opening control switch.

These and other features of the invention will be elucidated in conjunction with the accompanying drawings.

Figure 1 shows a schematic view of an embodiment of the combination according to the invention.

Figure 1 shows the stationary contact 1 and the movable contact 2 of a vacuum interrupter. Both contacts 1, 2 are shown in the cbsed position of the vacuum interrupter.

The movable contact 2 is connected via an actuator rod 3 to the movable pole body 4 of actuator 5. The actuator 5 furthermore has a static pole body 6. Both pole bodies 4, 6 have cavities in which a second electromagnetic coil 7 and a first

electromagnetic coil 8 is arranged. The first coil 8 is used to move the contacts 1, 2 to an open position, while the second electromagnetic coil 7 is used to move the contacts 1, 2 towards each other.

The stationary pole body 6 is furthermore provided with a permanent magnet 9, which will attract the movable pole body 4 once the contacts 1, 2 are in closed position. This ensures that the second electromagnetic coil 7 does not need to be powered during the complete period that the contacts 1, 2 are in the cbsed position.

Finally, a spring 10 is arranged between the movable pole body 4 and the stationary pole body 6 to ensure that the actuator and contacts 1, 2 maintain an open position and are not pulled to the closed position by the stationary magnet 9 abne.

A first circuit with the first electromagnetic coil 8 and a capacitor 12 is switched by a control switch 11, such that the pole bodies 4, 6 are urged away from each other to open the contacts 1, 2. A second circuit with the second electromagnetic coil 7 and a capacitor 13 is switched by a control switch 14, such that the pole bodies 4, 6 are pulled towards each other to cbse the contacts 1, 2.

The control switches 11, 14 are controlled by a micro-controller 15, which has an open command input 16 for receiving an opening command and an open output 17 connected to the switch 11. The micro-controller 15 has furthermore a close command input 18 for receiving a cbsing command and a close output 19 connected to the switch 14.

An external power supply 20 is provided which supplies power to a charger 21 for charging both capacitors 12, 13. The power supply 20 also provides voltage supply via an AC to DC converter 22 and via a DC to DC converter 23 to the power supply input 24 of the controller 15. During normal use, the external power supply 20 thus powers the controller 15, which can receive open commands from 16 after pressing switch 25 or 26 and or cbse command from 18 and according control the first and second electromagnetic coils 7, 8 such that the contacts 1, 2 open or cbse. This time second voltage converter 27 is disabled.

When the external power supply 20 fails, the micro-controller 15 will not be powered and signals on the open command input 16 and close command input 18 will have no effect.

According to the invention, an opening control switch 25, 26 is provided. The opening control switch 26 can be operated manually or the opening control switch 25 can be operated like a relay by an external circuit.

When external power supply fails and at least one of the opening control switches 25, 26 is closed, the DC to DC converter 27 will be enabled to power the microcontroller 15 from the first capacitor 12. At the same time, the open command input 16 will be activated, such that as soon as the micro-controller 15 is fully started the opening sequence will be performed, which includes cbsing control switch 11 such that the first capacitor 12 also powers the first electromagnetic coil 8 for opening the contacts 1, 2.

As the second capacitor 13 is connected to the first capacitor 12 via a diode 28 with the forward direction of the diode towards the first capacitor 12, the power of the second capacitor 13 can also be used for powering the micro-controller 15 and for energizing the electromagnetic coil 8 and thus open the contacts 1, 2 although the external power supply 20 fails.